Advanced Exergy-Based Audition of Heat Recovery Steam Generators: A Case Study

2021 ◽  
pp. 1-32
Author(s):  
Arvin Sohrabi Babouri ◽  
Ali Behbahaninia ◽  
Saeed Sayadi ◽  
Mohsen Banifateme
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Exergy Destruction ◽  
Steam Generators ◽  
Transfer Unit ◽  
Energy And Exergy ◽  
Loss Method

Abstract The current paper enhances the methods presented in ASME PTC 4.1 and 4.4 and proposes an exergy-based loss method for assessing heat recovery steam generators (HRSGs) performance. First, energy and exergy analyses are applied to one HRSG unit in an existing combined cycle power plant. Then, the calculated exergy destructions are further split into avoidable and unavoidable parts. The sources of inefficiency consist of three energy and exergy loss terms and two exergy destruction terms. The loss terms are associated with the release of the exhaust gas to the atmosphere, Carbon Monoxide formation, and the heat loss from the casing, while the destruction terms represent exergy destruction within the duct burner and the heat transfer unit. The advanced exergy analysis was conducted based on a realistic perspective, considering the integrated operation of both subcomponents. Results reveal that the main source of inefficiency corresponds to the losses associated with the exhaust gas from the stack. Moreover, utilizing semi-ideal heat exchangers can avoid a considerable part (18.8%) of the exergy destruction in the heat transfer unit. The HRSG exergy efficiency is obtained by 71.7% and can be increased to 75.3% in unavoidable operating conditions.

Modified Rankine HRSG Beats Triple-Pressure System

1996 ◽  
Author(s):  
Peter Eisenkolb ◽  
Martin Pogoreutz ◽  
Hermann Halozan
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Power Plants ◽  
Fossil Fuels ◽  
Combined Cycle ◽  
Exhaust Gas ◽  
Pressure System ◽  
Exergy Losses

Gas-fired combined cycle power plants (CCP) are presently the most efficient systems for producing electricity with fossil fuels. Gas turbines have been and are being improved remarkably during the last years; presently they achieve efficiencies of more than 38% and gas turbine outlet temperatures of up to 610°C. These high outlet temperatures require modifications and improvements of heat recovery steam generators (HRSG). Presently dual pressure HRSGs are most commonly used in combined cycle power stations. The next step seems to be the triple-pressure HRSG to be able to utilise the high gas turbine outlet temperatures efficiently and to reduce exergy losses caused by the heat transfer between exhaust gas and the steam cycle. However, such triple-pressure systems are complicated considering parallel tube bundles as well as start up operation and load changes. For that reason an attempt has been made to replace such multiple pressure systems by a modified Rankine cycle with only a single-pressure level. In the case of the same total heat transfer surfaces this innovative single-pressure system achieves approximately the same efficiency as the triple-pressure system. By optimising the heat recovery from the exhaust gas to the steam/water cycle, i.e. minimising exergy losses, the stack temperature is much higher. Increasing the heat transfer surfaces means a decrease of the stack temperature and a further improvement of the overall CCP-efficiency. Therefore one has to be aware that the proposed system offers advantages not only in the case of a foreseeable increase of gas turbine outlet temperatures but also for presently available gas turbines. Using existing highly efficient gas turbines and subcritical steam conditions, power plants with this proposed Eisenkolb Single Pressure (ESP_CCP) heat recovery steam generator achieve thermal efficiencies of about 58.7% (LHV).

Design Principles and Sizing Approach of Unfired Once-Through Steam Generators

2011 ◽  
Author(s):  
E. Hamid ◽  
M. Newby ◽  
P. Pilidis
Keyword(s):  
Heat Transfer ◽  
Power Systems ◽  
Heat Recovery ◽  
Power Plants ◽  
Design Principle ◽  
New Technology ◽  
Combined Cycle ◽  
Steam Generators ◽  
Scaled Model ◽  
Flow Rates

One of the key elements of increasing the thermal efficiency of a combined cycle power plant (CCPP) is to improve the design and operation of the heat recovery steam generators (HRSG) utilized in the cycle. Once-through steam generator (OTSG) is a new technology introduced for heat recovery in power systems. It eliminates boiler drums and other components of conventional HRSGs. The simplicity and compactness of an OTSG justifies its application in combined cycle power plants. This paper describes a design principle and an analytical sizing approach that will assist OTSG’s designers to achieve a good design by determining the core dimension, volume of an OTSG for given flow rates and their entering and leaving temperatures as well as the heat transfer area on the smoke side. The developed model has been tested with reference to a scaled model of an existing OTSG that is installed at Manx Electricity Authority and the results were promising. The overall characteristics of heat transfer and pressure drop distributions of the OTSG “scaled model” shows general agreement with the real characteristics of the existing OTSG with error values less than 1%.

scholarly journals Gas Turbine Heat Recovery Steam Generators for Combined Cycles Natural or Forced Circulation Considerations

1988 ◽  
Author(s):  
Akber Pasha
Keyword(s):  
Gas Turbine ◽  
Steam Generator ◽  
Heat Recovery ◽  
Power Plants ◽  
Natural Circulation ◽  
Combined Cycle ◽  
Heat Recovery Steam Generator ◽  
Steam Generators ◽  
Forced Circulation ◽  
Gas Turbine Exhaust

In recent years the combined cycle has become a very attractive power plant arrangement because of its high cycle efficiency, short order-to-on-line time and flexibility in the sizing when compared to conventional steam power plants. However, optimization of the cycle and selection of combined cycle equipment has become more complex because the three major components, Gas Turbine, Heat Recovery Steam Generator and Steam Turbine, are often designed and built by different manufacturers. Heat Recovery Steam Generators are classified into two major categories — 1) Natural Circulation and 2) Forced Circulation. Both circulation designs have certain advantages, disadvantages and limitations. This paper analyzes various factors including; availability, start-up, gas turbine exhaust conditions, reliability, space requirements, etc., which are affected by the type of circulation and which in turn affect the design, price and performance of the Heat Recovery Steam Generator. Modern trends around the world are discussed and conclusions are drawn as to the best type of circulation for a Heat Recovery Steam Generator for combined cycle application.

Heat Recovery Steam Generators of Binary Combined-Cycle Units

2021 ◽  
Vol 68 (6) ◽  
pp. 452-460
Author(s):  
P. A. Berezinets ◽  
G. E. Tereshina
Keyword(s):  
Heat Recovery ◽  
Combined Cycle ◽  
Steam Generators

The Upgrading of the Combined-Cycle Cogeneration Plant with Heat-Recovery Steam Generators for Large Cities of the Russian Federation

2021 ◽  
Vol 68 (2) ◽  
pp. 110-116
Author(s):  
M. A. Vertkin ◽  
S. P. Kolpakov ◽  
V. E. Mikhailov ◽  
Yu. G. Sukhorukov ◽  
L. A. Khomenok
Keyword(s):  
Russian Federation ◽  
Heat Recovery ◽  
Combined Cycle ◽  
Cogeneration Plant ◽  
Steam Generators ◽  
Large Cities ◽  
The Russian Federation

scholarly journals How to Construct a Combined S-CO2 Cycle for Coal Fired Power Plant?

Entropy ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 19 ◽  
Author(s):  
Enhui Sun ◽  
Han Hu ◽  
Hangning Li ◽  
Chao Liu ◽  
Jinliang Xu
Keyword(s):  
Power Plant ◽  
Flue Gas ◽  
Heat Recovery ◽  
Water Cycle ◽  
Combined Cycle ◽  
Exergy Destruction ◽  
Generation Efficiency ◽  
Air Preheater ◽  
Recompression Cycle ◽  
Residual Heat

It is difficult to recover the residual heat from flue gas when supercritical carbon dioxide (S-CO2) cycle is used for a coal fired power plant, due to the higher CO2 temperature in tail flue and the limited air temperature in air preheater. The combined cycle is helpful for residual heat recovery. Thus, it is important to build an efficient bottom cycle. In this paper, we proposed a novel exergy destruction control strategy during residual heat recovery to equal and minimize the exergy destruction for different bottom cycles. Five bottom cycles are analyzed to identify their differences in thermal efficiencies (ηth,b), and the CO2 temperature entering the bottom cycle heater (T4b) etc. We show that the exergy destruction can be minimized by a suitable pinch temperature between flue gas and CO2 in the heater via adjusting T4b. Among the five bottom cycles, either the recompression cycle (RC) or the partial cooling cycle (PACC) exhibits good performance. The power generation efficiency is 47.04% when the vapor parameters of CO2 are 620/30 MPa, with the double-reheating-recompression cycle as the top cycle, and RC as the bottom cycle. Such efficiency is higher than that of the supercritical water cycle power plant.

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